Spectroscopic study and molecular dynamics of hybrid membranes for application as solid electrolytes

• Grant number: 25/05893-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: November 01, 2025
• End date: March 31, 2030
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Mauro Carlos Costa Ribeiro
• Grantee: Vinicius Matheus Silva Macedo
• Host Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/11983-4 - Spectroscopy signal enhancement: nanomaterials, theory, and computer simulation, AP.TEM

Abstract

A fuel cell (FC) is an electrochemical device that converts the chemical energy of a fuel directly into electrical energy. FCs combine high efficiency and low emissions, with various applications in transportation, portable energy, and stationary power generation. Among the aspects of FCs that require improvement are the solid electrolyte membranes, particularly proton exchange membranes, which are the focus of this doctoral project. In this project, we will develop hybrid membranes from mesoporous silica and its modified forms through doping with Al3+ cations. The polymeric electrolyte used will be derived from poly(ether ether ketone) (PEEK) through sulfonation, generating poly-sulfonated(ether ether ketone) (SPEEK). The hybrid membranes will be based on SPEEK with ionic liquids, particularly the class of protic ionic liquids, in order to increase proton conductivity. Among the most well-known mesoporous silicas of the MCM type, preference will be given to MCM-41, which features a hexagonal structure and a unidirectional pore system. The hybrid polymer electrolyte membranes will, therefore, be a ternary system: mesoporous silica, polymer, and ionic liquid. The structures of the prepared hybrid membranes will be analyzed by X-ray diffraction, the morphology and pore diameter will be investigated by SEM and N2 physisorption, and thermal stability will be evaluated by thermogravimetric analysis. Ionic liquids with different combinations of cations and anions will be employed, and the interaction of the ions with the polymer matrix will be assessed through vibrational spectroscopy (infrared and Raman). Specific temperature control accessories that allow for in situ Raman spectroscopy with calorimetric or electrical measurements will be used to investigate structural changes via Raman spectroscopy simultaneously with the observation of phase transitions or the measurement of the material's conductivity as a function of temperature. Additional data on the molecular interactions and structure of the hybrid membranes will be obtained through molecular dynamics simulation. (AU)